Process of treating brass and bronze secondary metals



Patented May 19, 193

Y UNITED STATES- 7 raocnss F TREATING naass'ann BRONZE sacommnr METALSJesse 0. Betterton and Albert J. Phillips,Me-

tuchen, N. J., assignors to American smelting and Refining Company, NewYork, N. Y., a corporation of New Jersey No Drawing. ApplicationDecember '1, 1933,

Serial No. 791,338. Renewed November 10...

' 11 Claims.

This invention relates to a process of selectively separating andrecovering metallic values from brass and bronze secondary metals.

By the present invention the alloy scrap, which I generally containscopper; zinc, tin and lead as its major constituents, is treated insuchmanner that sharp separations between the metallic values are readilyobtained and the waste and expense ordinarily involved in retreatingintermediate products to place samein marketable form are materiallyreduced or eliminated.

Other features and advantages of the=invention will be readily apparentfrom the process hereinafter described and more particularly set forthin the claims.

In accordance with the invention, the alloy scrap, after any desired ornecessary preliminary treatment, is charged to a converter and treatedin a manner adapted to selectively'removein successive stages the zincand tin contents, respectively. The copper, high in oxygen andcontaining a portion of the lead originallypresent, is then'removed fromthe converter and either cast or directly transferred to an anodefurnace from which it is cast into anodes.

The following description of the invention as applied to the treatmentof old radiators will serve to more fully illustrate the advantages of'the present invention and a specific manner in 3 which it may bepractised, but such description is not to be construed as in any mannerlimiting the invention.

The radiators, as received are first sweated to remove solder andmetallic iron, which can be readily severed, is removed. The radiatorsmay then be charged to an ordinary reverberatory furnace and the ironslagged. The molten charge is then transferred to an ordinary tiltablecon verter and a relatively thick bed or layer of coke or itsequivalent, say 10-20 inches, applied over the entire surface of thecharge.

The charge is then blown with air in the usual manner, but instead of amixed dust and fume of different elements (lead, tin and zinc) a fume 45high in zinc and low in other constituents. is oblayer of coke duringthe blowing the zinc oxide will pass off preferentially while part ofthe lead and nearly all of the tin will be retained in the bath. \Inaddition, this selective separation is very eflicient as the zinccontent of the metal can be reduced to less than 1%,-while at the sametime 80% or more of the tin is retained in the metal. When necessary thecoke layer is replenished to maintain a satisfactory layer of sameduring the entire time that the charge is being oxidized for theelimination of zinc.

When the zinc has been. removed to the limits desired (1% or less) thecoke layer is skimmed 5 or otherwise removed or materially reduced inthickness as by burning oil. If mechanically removed, it isadvantageously returned to the rever beratory slagging furnace with anew charge where it gives up the bulk of its tin, thus materiallyreducing waste of that element as the slag from the reverberatory is ofdiscard grade.

Following the removal of the coke layer from the converter, the chargeis further oxidized with the result that fume rich in tin and containingconsiderable amounts of lead but relatively little zinc is produced. Thetin that does not enter the fume is removed as a concentrated dross}from the converter. The copper remaining in the converter contains somelead and is saturated with oxygen and is, therefore, treated in an anodefurnace prior to being cast into anodes. 'Itlis thus apparentthat theprocess of the present invention, by reason of the selective separationseffected, is of decided commercialimportance and marks a distinctadvance over the processes heretofore employed. By reason of theselective removal of the zinc and tin, concentrated products areobtained which may readily be processed as marketable products. The em.-ciency of the process in making sharp separations between theconstituents is amply illustrated by the following example in whichscrap brass analyzing 75.2% copper, 5.6% lead, 5.3% tin and 13.9%-(by'diflerence) -zinc wascovered with a deep layer of coke and thecharge at a temperature of about 2300 F. was blown with air. As a resultthe zinc content of the charge was reduced "to only a trace, the.chargeanalyzing 89.5% copper, 4.3% lead and 6.2% tin. The coke layer was 40then removed and the blowing resumed whereby all of the tin was removedand the residual metal analyzed 99.2% copper and 0.4% lead.

While certain novel features of the invention have been disclosed andare pointed out in the annexed claims, it will be understood thatvarious omissions, substitutions and changes may be made by thoseskilled in the art without departing from the spirit of the invention.

What is claimed is: v

1. The process of treating scrap radiators which comprises in sequencesweating the radiators to remove solder, melting said radiators andslagging the iron present, charging themolten copper containingzinc,'tin and lead toan ordi- 65 nary converter under a layer of cokeapproximately 1040 inches thick, blowing the metal with air therebyeliminating the bulk oi the zinc as fume, removing the coke layer andcontinuing I the blowing thereby oxidizing the tin and recov- ,eringsame as dross and tin-rich fume, and thereafter treating the copper inan anode furnace preparatory to casting same into anodes and recoveringthe copper by electrolysis. 10

2. The process according to claim 1 in which additional coke is added tothe layer as the elimination of zinc progresses.

3. The process of treating brass or bronze secondary metals whichcomprises charging same to a converter, covering the entire surface ofthe molten metal with a layer of coke of substantial thickness andblowing the charge with air until practically all of the zinc isremoved, then re- -moving the coke layer and continuing the blowinguntil practically all of the tin is removed from the metal andthereafter refining the copper in an anode furnace and electrolyzing theanodes cast therefrom.

4. The process of treating brass or bronze secondary metals whichcomprises charging same to a reverberatory furnace to slag iron,transferring the =molten metal to a converter, covering the entiresurface of the molten metal with a layer of coke of substantialthickness and blowing the charge with air until practically all of thezinc is removed, then removing the coke layer and continuing the blowinguntil practically all of the tin is removed from the bath, andthereafter treating the copper in an anode furnace and electrolyzing theanodes cast therefrom.

5. The method of selectively-separating zinc and tin from copper alloyscrap which comprises,

covering a molten bath of said scrap with a dense layer of coke andblowing the bath with air thereby preferentially eliminating the zinc asfume, removing the coke layer when substantially all of the zinc hasbeen eliminated and continuing the blowing thereby eliminating tin as atin-rich fume and dross.

for the production of copper anodes suitable for I I I v v 7. The methodof treating copper alloy scrapcontaining lead, tin and zinc whichcomprises establishing a molten bath of the scrap in a converter,covering the entire surface of the molten metal with a dense layer ofcoke and blowing the bath with air thereby eliminating zinc from thebath as a rich zinc fume, removing the coke layer when the zinc contentof the bath is reduced below one percent and continuing the blowing ofthe bath thereby eliminating tin as dross and rich tin fume andthereafter refining the copper in an anode furnace for the production ofcopper anodes suitable for electrolysis.

8. The process for treating copper alloy scrap to selectively removezinc and tin as concentrated oxide products which comprises blowing amolten bath of such scrap with air under a dense layer of coke andmaintaining the thickness of said layer by additions of coke as theblowing progresses thereby eliminating the zinc in concentrated formwithout removing substantial amounts of tin, materially reducing thethickness of the coke layer to at most a thin layer when substantiallyall of the zinc has been eliminated and continuing the blowing therebyremoving the tin in concentrated form.

9. The method of selectively separating zinc and tin from brass orbronze secondary metal which comprises covering a .molten bath of suchmetal with a coke blanket of substantial thickness and blowing the bathwith air thereby preferentially removing the zinc, removing the bulk ofthe coke layer when practically all of the zinc has been eliminated andcontinuing the blowing with air thereby removing the tin.

10. In treating copper alloys containing tin and zinc by blowing airthrough a molten bath of such alloys, the improvement which consists inperforming the operation under cover of a layer ofsuitable carbonaceousreducing material sufficiently thick to efl'ectively prevent removal ofthe bulk of the tin from the system while simultaneously permitting thevolatilization and removal of practically all of the zinc.

11. The process for treating copper alloys containing tin and zinc whichconsists in blowing air through a molten bath of such alloys whileblanketing said bath sufliciently to prevent removal of the bulk of thetin from the bath while simultaneously permitting the voltalizaion ofpracti-- cally all of the zinc and thereafter concentrating the tincontent in a substantially zinc free state.

JESSE BE'I'I'ERTON. ALBERT J. PHILLIPS.

